Some current client-side messaging systems and other derivatives run at a single location—i.e., related messaging software may execute on a single client machine. These systems may sense a user's presence (including the monitoring of keyboard and mouse activity, and/or monitoring of ambient acoustical activity via a microphone), at a local machine to make decisions about whether to consider executing mobile alerting by routing to a mobile device, some subset of messages that might be typically displayed to a user on a client application in situations where the user is present at the client device. If users are present at the local client, it is generally desired to suppress mobile messaging as such messages will be redundant with messages that have been or will soon be viewed by users. Simply stated, users generally do not want to be paged with messages when they are or will soon be receiving the messages at their client machines.
In earlier versions of these client-side systems, a deterministic or predicted time that a user has not been or will not be present at a client machine, respectively, is considered before mobile alerting is allowed. This limits mobile alerting to situations whereby a user will not see immediately, or will not soon see an email message so as to minimize the cost and annoyance of having email come to a paging device when the user will see it immediately or will soon see the messages at the client machine.
Providing the users with the ability to specify some finite amount of predicted away time, or time away that has already passed, before invoking mobile messaging allows a valuable buffer, that handles the case where a user is coming and going from the client machine, and still prefers to receive messages on the client machine, but that can also switch to mobile messaging if the delays either reach a threshold delay or are expected to reach a threshold. Timing can refer to the age of each message (the difference in time since it arrived or was sent and the current or predicted time that a user will be away), it can also be used to simply refer to the time that a user has not been present at the client machine. Threshold times before invoking mobile messaging can be fixed or made a function of the urgency of messages. Beyond the use of a delay for buffering to minimize the transmittal of messages via a mobile link or another alternate route to the user (e.g., another email address, telephone call with conversion of text to speech, etc.), in cases where a user will soon return to see a message, such a time delay bounds the total cost associated with the delayed relay of a message to a user. Putting specific limits on delays before a user sees messages depending on urgencies of messages bounds the losses associated with delays. Such bounded deferral policies allow for a characterization of maximal cost.
One problem with the client-side presence approach, and other client-side or local decision making about alerting via a transfer to a mobile device, is that a user can be falsely alerted when only client-side presence is considered. In one example, a user of this type messaging system typically executes a respective mobile routing application on a single machine. The user may then carry a mobile laptop to a meeting in a different building or may access email at a kiosk at a distant airport. When logged in at a distant site, email may be read via another communication with the user's email server (e.g., Microsoft Exchange server). Thus, a user's time away from their client device, which is locally executing a mobile routing program, may exceed some threshold time, leading to mobile alerting, when that user is actually intermittently reading email on another device, with delays that would be under the set threshold. Thus, even though users are receiving messages within the allowances of some predefined time, they are being alerted redundantly because there is no information available to the client-side message routing system about the user's presence at other machines; the messaging application at the user's office simply considers the user as being away.